Moulded bodies, in particular fibres and the structures thereof exhibiting thermoregulation properties

ABSTRACT

The invention related to a method for producing molded bodies made of cross-linked native polymers in such a way that a network is formed by chemically coupled functional groups, hydrogen bridges or polymer or oligomer structures helically connected to each other and up to 200 mass % of micro-encapsulated phase change material is included into a polymer matrix with respect to the cross-linked polymer. Said cross-linked polymers can, for example be embodied in the form of polysaccharides and/or globular proteins. In the form of fibers the molded bodies can be processed to textile fabrics having enhanced thermoregulation properties and an improved wearability to the textiles produced therefrom, as well as a high functionality with respect to heat storage and heat removal when used in other applications.

Object of the invention is a method of producing molded bodies consisting of native polymers forming networks and phase change materials included therein, which in the form of fibers can be processed to textile fabrics having enhanced thermoregulation properties and which convey an improved wearability to the textiles produced therefrom, as well as a high functionality with respect to heat storage and heat removal when used in other applications.

PRIOR ART

Thermoregulation properties of polymer fibers are generated in that phase change materials are applied on to or inserted into a polymer matrix. When changing their phasing or their conformation, phase change materials can absorb and emit, respectively, large amounts of heat at constant temperatures. At the moment of a phase change or a change of conformation an increased heat capacity can be noticed which finds its physical measurable expression in the occurring melting enthalpy and permits the storage or delivery of greater amounts of heat than would correspond to the normal heat capacity of the material outside of the temperature range of the phase change or the conformation change. The absorption of heat at a change of the phasing or of the conformation is, on the one hand, due to the absorption of thermal energy at a heat supply from outside, which subjectively is felt as a cooling effect, and on the other hand, when there is a cooling, reversibly supplies in the reverse direction the same amount of heat, which is felt as warming. Paraffin or salts and solutions of suitable salts, respectively, can be used as phase change materials. When paraffin are used, the temperature range of the phase transition from the solid state into the molten state can be, due to varying the chain length, controllably matched to each desired temperature at which the heat is to be delivered or stored. Salts or the solutions thereof can be selected at will to the desired temperature range of the conformation change. Particularly the micro-encapsulated form is suited for use in the textile technology. In this case the phase change material is encased in ceramic spheres and polymer spheres, respectively, having diameters within the μm-range and in this manner are brought into a form that can be manipulated and that permits the inclusion in matrix materials of cross-linked polymers, whereby the degree of the thermo regulation potential depends on the kind and the amount of the enclosed PCM material. Synthetic polymers as well as native network forming polymers can be used as matrix materials.

Fibers having thermo-regulating properties and textile fabrics made therefrom are already known per se. So the teaching of EP 0306202 and U.S. Pat. No. 4,756,958 is that synthetic fibers from melt-spinnable polymers can be provided with temperature stabilizing behaviour by including therein temperature regulating materials. A disadvantage thereby is the low amount of temperature regulating materials that can be inserted into the fibers. Furthermore, clothing is described in U.S. Pat. No. 5,885,475 which is composed of fibers made of a mixture of polymers which additionally includes phase change material. Also here the fiber-forming substances are selected from the group of synthetic thermoplastic polymers which can be spun when molten.

Multi-component fibers with enhanced and reversible thermal properties and textile fabrics manufactured therefrom are described in WO 03027365, US 200212079, and US 200129648. The fiber bodies which consist of a plurality of elongated components contain at least in one of said elongated components one temperature regulating material distributed therein. This material may be a phase change material and may optionally be selected from the class of the hydrocarbons, the hydrated salts, paraffin, oil, water, fatty acids, fatty acid ester, dibasic acids and ester, halide, clusters and semi-clusters, gas-cluster, stearin anhydride, carbonate ethylene, higher alcohols, polymers, and metals and mixtures thereof.

The arrangement of the different components of the fiber can be optionally arranged in a core-sheath-structure, polysectionally, in bundles or in stripes with variously formed cross-sections. The matrix material of the multi-component fiber described may consist of different linear chain molecules.

Its is disadvantageous with these fibers and the textile fabrics manufactured from said fibers that, due to the described arrangement of the individual components, only a part of the fibers formed from said components contains phase change material, and the part of the temperature regulation material in the entire fiber is, naturally, limited. Due to the presence of multi-component-structures made of a plurality of elongated components the portion of phase change material which can be inserted into the polymer structure is limited to a portion of maximally 50 weight percent related to the respective matrix material.

In WO 02095314 and CH 0200245 there are also methods described in which the temperature regulation properties are to be obtained by textile printing of a textile fabrics structure with micro-encapsulated phase change material. In other words, the temperature regulation effect is obtained by applying a coating which contains a phase change material. Such a method, however, involves the disadvantage that only a comparatively low amount of phase change material can be fixed to the surface of the structures, in particular when only a part of the surface is printed with a suspension of micro-encapsulated phase change material and, hence, the temperature regulation effect, related to the amount of material, is comparatively locally limited. Additionally, the printing of the textile surface with a suspension of micro-encapsulated phase change material applied in a comparatively thick layer has a disadvantageous effect on the flexibility of the textile products manufactured therefrom and, hence, on the wearability. Furthermore, the suspensions of micro-encapsulated phase change materials applied to textile surfaces are only restrictedly mechanically stable and fast to washing.

In US 2003124278 and US 2003124318 an arrangement of textile materials in layers is described which are provided with temperature regulation properties in such a manner that the micro-encapsulated phase change materials are enclosed between them. Such a layer setup has the disadvantage that the exchange of heat through the external layers is obstructed and so the heat capacity of the enclosed micro-encapsulated phase change material can only be utilized to a limited degree. Due to the lack of bonding the micro-encapsulated phase change material to the material of the base structure, both, the amount of introducible phase change material and the capability of an effective heat transfer to the phase change material are limited.

A similar arrangement is disclosed in U.S. Pat. No. 6,217,993 and U.S. Pat. No. 6,077,597.

Nearly all the PCM-fibers described herein before are manufactured on the basis of synthetic melt-spinnable polymer fibers. The use of network forming matrix material which occurs in nature and can be obtained in a simple way such as cellulose and/or globular proteins has neither been mentioned before, nor have exemplary PCM-fibers been produced therefrom.

It is known that cross-linked structures can be, for example, manufactured from cellulose form matter and spinning matter in that cellulose is dissolved in tertiary amino oxides, preferably in n-methylmorpholin-n-oxide and a non-solvent agent, preferably water. In this case a spinning solution consisting of cellulose in n-methylmorpholin-n-oxide and water is molded after a dry/wet-spinning process, coagulated for example in an aqueous spinning bath, the solvent is completely removed by repeated washing and the solidified molded bodies are dried. The molded bodies obtained in this manner exhibit a network structure characterized by a hydrogen bridge linkage. (Refer to Berger, W.: Möglichkeiten und Grenzen alternativer Cellulosauflösung; Lenziger Berichte 74 [1994] 9, pg. 11-18).

DE 10059111 teaches the cross-linking of proteins via the existing functional groups which results in mechanically stable molded bodies. The globular proteins exhibit, as the name already tells, a spherical tertiary structure and can be found in nature in a comparatively great number. Examples for these are casein (a lactic protein), zein (corn protein) and ardenine (arachis protein).

OBJECT OF THE INVENTION

The object of the invention is to provide a method for producing thermo regulating molded bodies, in particular fibers and nonwoven textile fabrics thereof from native network forming polymers having phase change material included in the network which in contrast to PCM-fibers produced on a synthetic basis have an increased portion of incorporated phase change materials and thus, in avoiding the mentioned disadvantages of the prior art, exhibit an enhanced thermo regulation potential.

Furthermore, an aspect will be the application of parent materials occurring in nature and the environmental-friendly production of fibers having the described properties by the fewest possible process steps under exploitation of natural resources.

According to the invention the object is realized in that phase change materials up to an amount of 200 weight percent are included into network forming polymers, wherein the network is formed by chemically coupling functional groups, hydrogen bridges or polymer and oligomer, respectively, structures helically connected to one another.

A suitable network forming polymer matrix material is native cellulose. The latter forms bonds which, on the one hand, effect a cross-linkage of the polymer structure and, on the other hand, result in the formation of a super lattice structure due to the developing of hydrogen bridge linkages. This structure formation permits the embedment of even larger amounts of micro-encapsulated phase change materials. The micro-encapsulation results in a separation of the phase change material from the polymer matrix. For example, paraffins of different chain lengths will be used as phase change materials, whereby the temperature of the phase transition depends on the chain length of the molecules and can be adapted to the required temperature range of the phase transition by varying the chain lengths. But inorganic hydrated salts can also be utilized which can be selected in dependence on the desired temperature range of the phase change. Due to their higher density compared to paraffins it is possible in particular, to insert far more than 50 weightpercent of phase change material into the polymer matrix.

Globular proteins which are present in nature in a great number and which can be extracted in a simple manner are further network forming polymer materials, which are suitable for realizing the object of the invention. Starting from a primary structure based on peptide bonds, a three-dimensionally interlinked tertiary structure results in these proteins via a secondary structure in the form of the folded-up amino acid chain, based on a hydrogen bridge linkage. Said tertiary structure will be stabilized, for example, via disulphide bridges, hydrogen bridge linkages or by ion- or hydrophobic interactions. It was surprisingly found in DE 10059111 that pre-interlinked globular proteins are also soluble in tertiary amino-oxides and could be molded in a dry/wet-process. Furthermore, it is possible to add a polysaccharide as, for example cellulose, as a further component to the solution of the pre-interlinked globular proteins. Thus the chance is given to affect at will the properties of the molded bodies.

In a particularly preferred embodiment of the inventional solution phase change materials up to an amount of 200 weightpercent, related to the mass of the contained cellulose, are, for example, added to a cellulose solution in an aqueous tertiary aminoxide, and this solution drafted via an air gap and subsequently the cellulose with the phase change material contained therein is precipitated in a coagulating bath consisting of, for example, water or a water/alcohol mixture under formation of physical networks. After the depleted extraction of the solvent the following drying process leads to the formation of hydrogen bridge linkages which in spite of the comparatively high amount of phase change material permit a sufficiently high textile-physical stability for application of the molded bodies in, for example, apparel textiles. The cross-linkage of the polymer matrix provides for a complete and mechanically stable inclusion of the micro-encapsulated phase change materials in addition to an optimal heat transfer into and from out of, respectively, the phase change material.

In another embodiment of the inventional solution, micro-encapsulated phase change material is added to pre-crosslinked globular proteins in n-methylmorpholin-n-oxide, if necessary under addition of polysaccharides such as cellulose, are transferred into a spinning solution and spun to filaments by using known methods.

The produced PCM-fibers according to the invention based on native polymers find a wide range of applications such as, for example, in material for producing textiles, fleeces, textiles for the automobile industry, and in yarns and blended yarns.

The phase change heat, characterizing the thermo regulation properties of the inventional native PCM-fibers exhibits, compared to the PCM-fibers based on synthetic polymers a value which is up to a factor of 8 higher.

The invention will be explained in more detail hereinafter by virtue of examples of embodiment.

EXAMPLES Example 1

15779 g of a 60%-solution of n-methylmorpholin-n-oxide are given into a dissolving vessel with agitator of 37 l volume together with 1160 g cellulose of an average polymerisation degree 500 and 464 g (=40% related to the employed amount of cellulose) micro-encapsulated phase change material of a phase change temperature of 28° C. (Thermasorb® TY 83 of Frisby Technologies Inc.) under addition of 6.8 g propylgallate. The micro-encapsulated phase change material has been screened before to a grain size of maximally 50 μm. The dissolving vessel will be evacuated to 20 mbar and is heated from 20° C. to 94° C. in the course of 6 hours at a stirrer RPM of 18 min⁻¹ und the evaporating water is condensed in a connected condenser. The spinning solution obtained exhibits a viscosity of 1560 PAS and a refractive index of 1.484. At a spinning pump RPM of 25 min⁻¹ the spinning solution is at 80° C. extruded through a spinneret having a number of nozzles of 150 and a nozzle diameter of 200 μm via an air slot into a coagulating bath consisting of water. The drain speed is 25 m/min so that a draught of 3.75 results at the air slot. The spun fibers exhibit a titre of about 14 dtex and will subsequently washed in washing baths and then are cut to staple. The phase change temperature of the obtained fibers is 30 J/g.

Compared thereto, cellulose fibers without embedded phase change materials exhibit a heat capacity of 6 J/g. The breaking strength related to the count of the obtained fibers is about 15 cN/tex. The modified fibers could be processed to a needle fleece having a flat mass of 300 g/m² after carding in a carding engine.

Example 2

100 g casein are dispersed in 250 ml water and crosslinked by addition of 2 g glutaraldehyde and 0.1 g MgCl₂ at 25° C. After squeezing out to a moisture content of 50%, the casein is suspended in 430 g of 60%-NMMNO. 0.5 g propylgallate are added as a stabilizer. 100 g of a micro-encapsulated phase change material such as, for example, Lurapret® TX PMC 28 from BASF AG are added to the suspension what corresponds to an amount of 100 weightpercent of phase change material related to the protein in the solution. The suspension is transferred into a spinning solution in a kneading machine with a jacket heating under a vacuum of 30 mbar and at a temperature of 90° C. by distilling off of 130 g water. The homogeneity of the spinning solution is checked with an optical microscope and turns out, as a rule, 15 minutes after the end of the distillation. The spinning solution is extruded at a spinning temperature of 80° C. in filaments through a spinneret having 150 nozzles each of a diameter of 90 μm via an air slot into an aqueous coagulating bath and subsequently is washed in distilled water without residue and then cut to a staple length of 40 mm. The drying of the fibers is carried out at 60° C. in a through-circulation drier. The strength of the spun fibers is about 15 cN/tex at an elastic stretch of 10% and a titre of about 15 dtex. The heat absorption capacity of the obtained fibers is about 60 J/g compared to 8 J/g of the non-modified fibers.

Example 3

50 g casein are dispersed in 250 ml water and crosslinked by addition of 1 g glutaraldehyde and 0.1 g MgCl₂ at 25° C. After squeezing out to a moisture content of 50%, the casein is suspended in 430 g of 60%-NMMNO. Additionally 25 g of dry ground sulphite cellulose (DP 760) as well as 100 g of a micro-encapsulated phase change material such as, for example, Lurapret® TX PMC 28 from BASF AG are added. This corresponds to an amount of 133% PCM related to cellulose. 0.5 g propylgallate are added as a stabilizer. This suspension is transferred into a spinning solution in a kneading machine with a jacket heating under a vacuum of 30 mbar and at a temperature of 90° C. by distilling off of 140 g water. The homogenisation of the spinning solution is achieved 15 minutes after the end of the distillation and is checked with an optical microscope. The resulting spinning solution is extruded through a spinneret having 150 nozzles each of a diameter of 90 μm via an air slot into an aqueous coagulating bath and the formed fiber skein is washed in distilled water without residue and then cut to a staple length of 40 mm. The drying of the fibers is carried out at 60° C. in a through-circulation drier. The fibers exhibit a strength of 30 cN/tex at an elastic stretch of 8%. The titre is about 20 dtex. The heat absorption capacity of the modified fibers is about 70 J/g compared to 7 J/g of the non-modified fibers.

Example 4

7607 g of a 60%-solution of n-methylmorpholin-n-oxide are given together with 784 g cellulose of an average polymerisation degree 500 under addition of 4.6 g propylgallate into a dissolving vessel with agitator of 37 l volume. The dissolving vessel will be evacuated to 20 mbar and is heated from 20° C. to 94° C. in the course of 6 hours at a stirrer RPM of 18 min⁻¹ and the evaporating water is condensed in a condenser. Thereby 2361 g water are, in total, condensed. The spinning solution obtained exhibits a viscosity of 8072 PAS, the refractive index of the spinning solution is about 1.487.

Furthermore, a stock solution will be produced from 1500 g of an 80%-solution of n-methylmorpholin-n-oxide and 750 g of a micro-encapsulated phase change material such as, for example, Lurapret® TX PMC 28 from BASF AG and 45 g xanthane. Both solutions are, after intimate mixing in a dynamic mixer, extruded at 80° C. through a spinneret having a number of nozzles of 150 and a nozzle diameter of 200 μm, drafted through an air gap, regenerated in an aqueous coagulating bath and is washed in distilled water to be entirely free of solvents. The setting of the mixing ratio is carried out such that the extruded fibers exhibit a concentration of micro-encapsulated phase change material of 60% related to the cellulose. The spun fibers have a fiber count of about 10 dtex and are cut to staple after washing. The phase change heat of the achieved fibers is 80 J/g. In contrast thereto the cellulose fibers without an inserted phase change material exhibit in the corresponding temperature range a heat capacity of 6 J/g. The tenacity related to the fineness of the obtained fibers is about 15 cN/tex. 

1. Method for producing molded bodies, in particular fibers and textile fabrics thereof, with thermo-regulation properties on the basis of network forming polymeric matrix materials dissolved in aqueous amino oxides, preferably in n-methylmorpholin-n-oxides, characterized in that up to 200 weightpercent of a micro-encapsulated phase change material, related to the network forming polymer, are inserted into a matrix network setup of polysaccharides and/or globular proteins in such a way that either a) the micro-encapsulated phase change material is given as a component directly into the suspension consisting of the polymer, the aqueous n-methylmorpholin-n-oxide solution and propylgallate as a stabilizer into a dissolving vessel with stirrer, or b) in the case of the globular protein, used as polymer, after the pre-interlinking of the former the micro-encapsulated phase change material is given together with the aqueous n-methylmorpholin-n oxide solution and the propylgallate as a stabilizer, and, if necessary, with a further network forming polymer such as, for example, cellulose, into a jacket heated kneading machine, then the dissolving vessel and the kneading machine, respectively are evacuated, the suspension is heated, stirred, the water is evaporated and fibers are molded from the respectively achieved highly viscous spinning solution after a dry/wet-extrusion process or c) the micro-encapsulated phase change material is mixed together with an aqueous n-methylmorpholin-n-oxide solution to a stock solution, and the latter is given to an already completed spinning solution consisting of an aqueous n-methylmorpholin-n oxide solution, polymer and propylgallate as stabilizer and, by intimately mixing both, the solutions are given into a mixer, and from the high viscous spinning solution achieved in this manner also fibers are molded after passing a dry/wet extrusion process.
 2. Method as claimed in claim 1, characterized in that polysaccharides and/or polysaccharide derivatives are employed as network forming polymers, which are formed from hexoses with glycosidic 1,4-bonds and 1,6-bonds or at least partially from uronic acids.
 3. Method as claimed in claim 1, characterized in that as the network forming polysaccharides are cellulose and/or cellulose compounds.
 4. Method as claimed in claim 1, characterized in that a water-soluble homopolysaccharide or a heteropolysaccharide or the derivates thereof are inserted as polysaccharides.
 5. Method as claimed in claim 1, characterized in that the network forming polysaccharides are native globular proteins.
 6. Method as claimed in claim 1, characterized in that natural globular proteins are, by aid of aldehydes such as, for example, glutaraldehyde, pre-interlinked via amino-groups and/or amide groups and/or imino-groups of the peptide bonds and/or oxy-groups of the serine and/or cysteine components.
 7. Method as claimed in claim 1, characterized in that up to 99.5 weightpercent of polysaccharides and 0.5 to 100 weightpercent, preferably 60 to 90 weightpercent of globular proteins are inserted, related to the entire mass of the solved compounds.
 8. Method as claimed in claim 1, characterized in that micro-encapsulated phase change materials such as Thermasorb® TY 83 of Outlast Technologies Inc., which have been screened before to a maximal grain size of 50 μm, or Lurapret® PMC 28 of BASF AG are employed. 